DESCRIPTION: Neurotrophins are known to control not only neuronal survival, but may modulate phenotypic differentiation and adult neuropathic pain. In transgenic mice overexpressing NT-3 or NGF, changes are noted in sensory neuron number, projections and pain threshold. The collaborating lab has the ability to determine the "Comprehensive phenotype" of adult sensory neurons, using intracellular recording and labeling. These techniques will be used to examine individual sensory neurons of control and transgenic mice to assess if neurotrophin overexpression alters the phenotype (aims 1 and 2). It is also hypothesized that neuropathic pain recapitulates neurotrophin dependent processes. In aim 3, the phenotype of neurons responsible for neuropathic pain will be characterized, and antineurotrophin antisera will be used to block formation of the sympathetic/sensory neuron connections thought to mediate neuropathic pain.